Dispensing caps typically include two moulded plastic components which are connected together and are relatively movable between a first position, in which the bottle, to which the cap is connected, is sealed and a second position, in which the interior of the bottle communicates with the exterior through one or more openings through which a liquid in the bottle may flow. Such caps thus provide a resealing facility and, in the case of a drinking cap, the ability to drink from the bottle without removing the cap. However, the two separate components must be moulded separately and then connected together. This is both time-consuming and expensive.
One-piece dispensing caps are known and DE-G-8518074.2 discloses such a cap of the type including a first circular section tubular portion with a first radius for connection to the mouth of a container and a second circular section tubular portion with a second radius smaller than the first radius, the first tubular portion being connected to the second tubular portion by a resilient, annular, integral web, in which one or more flow openings are formed, the width of the web being equal to or greater than the difference between the first and second radii, one end of the second tubular portion being closed, one of the web and the internal surface of the first tubular portion being connected to a projecting annular first sealing flange, the first and second tubular portions being coaxial and relatively movable in the axial direction between an open position, in which the flow openings are unobstructed, and a closed position, in which and the sealing flange is in sealing engagement with the other of the web and the internal surface of the first tubular portion, whereby the flow openings are prevented from communicating with the atmosphere by the sealing engagement of the first sealing flange with the other of the web and the internal surface of the first tubular portion. However, the cap disclosed in this document is for dispensing powdery solid materials and not liquids and would be inherently unsuitable for use on a liquid container because it is incapable of forming a reliable liquid seal. Thus when the cap is in the closed configuration, the sealing flange and the web are in surface contact. Such surface contact is incapable of providing a reliable seal because the contact force is inherently very low and exerted over a substantial area, whereby the contact pressure is extremely small. As a matter of practice, it is impossible to form the two engaging surfaces completely smooth and complementary and the resulting inevitable gaps will mean that any liquid in the container will be subject to leakage.